Learn about the new politics and diplomacy systems in the latest free patch for Total War: ROME II with this handy guide.
When selecting factions for a campaign, you can also take control of the ruling political party, whereupon your faction's leader will become the head of said party.
When in the campaign, click on the faction button to bring up the political tab. The government overview is displayed on the left-hand side, here you can see how much influence a party has in your nation's government. Hover your cursor over each colour to view more information about each party.
Each political party that is currently in your empire is listed to the right, each have their own traits which will affect their loyalty towards you.
Next to that are the party statistics. How many senators a political party owns are displayed here, as well as the loyalty this party has to your rule. If this goes into minus after the first 20 turns of your campaign there is potential for the party to break away from you, taking the general and any provinces they have influence over, forming a new faction.
You can also take actions against each political party to either secure their loyalty for a short amount of time, or provoke them. This may lead to a secession, allowing you to deal with them before they get out of control. Tread carefully as this can lead to civil war.
Lastly, statesmen can be sent on missions in the character tab, these will give bonuses to a certain area of your campaign along with improving their party's loyalty to your house.